Two-dimensional electrophoresis is an effective way to analyze complex mixtures of proteins. Typically, two-dimensional electrophoresis involves separating the protein mixture by the intrinsic charge characteristics of the proteins, i.e., their isoelectric points, in a first dimension by a type of electrophoresis called isoelectric focusing, and then separating the protein mixture in a second dimension by electrophoresis. In the second-dimension electrophoresis, a gel strip containing the proteins separated in the first dimension is incubated in a buffer appropriate for the second-dimension electrophoresis, and applied to a second-dimension vertical or horizontal slab gel so that the proteins can be electrophoresed out of the first-dimension gel and into the second gel under appropriate conditions to separate the proteins on the basis of molecular mass.
The first-dimension electrophoresis, i.e., isoelectric focusing, is usually performed on thin flat strips of polyacrylamide gel containing a covalently immobilized pH gradient, i.e., IPG gel strips. The IPG gel strips are commercially available in a dehydrated state and are rehydrated in an appropriate buffer before use. One or more gel strips are carried by a gel carrier module during isolectric focusing. The gel carrier module is provided on an isoelectric focusing unit for isoelectric focusing of the protein mixture test sample.
A problem with present processes and systems for IPG gel strip preparation and isoelectric focusing (IEF) is that the process takes too long, i.e., up to two days to complete. Part of this problem stems from the isolectric focusing time, i.e., IEF separation time, taking too long. One reason for this long IEF separation time, which has been recognized by the inventors of the present application, is that IEF separation time is limited by the maximum rated voltage for the unit (usually.ltoreq.3500 V).
Another problem with present isoelectric focusing units having heat exchangers is that the heating and cooling systems and electrophoresis power supply are separate from the electrophoresis unit, occupying large amounts of bench space in a laboratory.
Another problem with present isoelectric focusing units is that they require considerable hands-on time in set-up and operation. Present gel carrier modules have their own power attachments, e.g., power cords, electrical leads, electrodes, etc., that must be connected with the power attachments of the electrophoresis device. Electrically connecting all of the power attachments of the gel carrier module to all of the power attachments of the electrophoresis device is time consuming, and can be done incorrectly, causing IEF problems and safety concerns.